Information processing in sensory systems

描述(由申请人提供)：该提案的主要目标是了解听觉系统中丘脑皮质早期处理阶段的功能组织。这涉及到对连接下丘(1C)、内侧膝状体(MGB)以及第一和第二听觉皮质(A1和ALL)的各种通路有更好的功能理解。我们将使用小鼠大脑的体外切片制备，在不同的切片配置中，1C到MGB，MGB到AI/AII，A1到MGB，以及A1到所有通路都完好无损。我们将通过光刺激或最小的电刺激来取消谷氨酸的去化，以测试每条通路的功能。特别是，我们将试图将每条路径识别为驱动程序(即信息的主要传输者)或调制器，并通过识别驱动程序，希望构建信息流的功能层次结构。这将使我们能够检验这样的假设，即系统中信息流动的主要途径是从中央1C(ICC)到MGB腹侧部分(MGBv)，再到A1到背侧MGB(MGBd，我们认为这是一种更高级别的丘脑中继)。这与传统的观点不同：一种是ICC到MGBv到Al和1C(IC)到MGBd到All的壳层区域的平行路径；另一种是从ICC到MGBv到Al到All的路径。这些关于职能组织的假设并不是相互排斥的，可能存在组合。尽管如此，我们必须更好地了解听觉信息是如何通过皮质处理的最初几个阶段进行传递的，然后我们才能开始了解这些途径中的病理如何导致听力问题。也就是说，认知听觉功能，如词汇-语义加工、语音信息提取、选择性注意和物体识别，几乎肯定是由听觉皮层网络辅助的，我们必须更好地理解这些网络。

DESCRIPTION (provided by applicant): The broad goal of the proposal is to understand the functional organization of the early thalamocortical stages of processing in the auditory system. This involves a better functional understanding of the various pathways connecting the inferior colliculus (1C), medial geniculate body (MGB), and first and second auditory cortices (Al and All). We will use an in vitro slice preparation of the mouse brain in which different slice configurations will have the 1C to MGB, MGB to AI/AII, Al to MGB, and Al to All pathways intact. We will use uncaging of glutamate by photostimulation or minimal electrical stimulation to test the function of each of the pathways. In particular, we shall attempt to identify each pathway as a driver (i.e., main conveyer of information) or modulator, and by identifying the drivers, we hope to construct a functional hierarchy of information flow. This will allow us to test the hypothesis that a main route of information flow in the system is from the central 1C (ICc) to the ventral portion of MGB (MGBv) to Al to the dorsal MGB (MGBd, which we suggest is a higher order thalamic relay) to All. This is contrasted to conventional views: one is of parallel paths of ICc to MGBv to Al and shell region of 1C (ICs) to MGBd to All; another is a path from ICc to MGBv to Al to All. These hypotheses of functional organization are not mutually exclusive, and combinations may exist. Nonetheless, we must obtain a better understanding of how auditory information is routed through the first few stages of cortical processing before we can begin to understand how pathology in these pathways can lead to problems in hearing. That is, cognitive auditory functions, such as lexical-semantic processing, phonological information extraction, selective attention and object recognition are almost certainly subserved by auditory cortical networks, and it is these networks that we must better understand.